# -*- coding: utf-8 -*-
"""
Created on Mon Sep 11 18:54:50 2017

@author: Administrator
"""

import numpy as np
import matplotlib.pyplot as plt

def sigmoid(z):
    return 1.0/(1.0+np.exp(-x))

x=np.arange(-30,30)
y=sigmoid(x)
plt.plot(x, y, linestyle=':', color='#FF0000', marker=".")
plt.show()